Reversible cooling fan



July 1, 1969 R. D. PHIL'IPSEN ETAL 3,452,820

REVERS IBLE COOLING FAN Filed Mnv 29, 1968 INVENTORS RICHARD D. PHILIPSEN KENNETH E. STARR ATTORNEYS United States Patent O 3,452,820 REVERSIBLE COOLING FAN Richard D. Philipsen, Peoria, and Kenneth E. Starr, Manito, Ill., assignors to Caterpillar Tractor Co., Peoria, Ill., a corporation of California Filed May 29, 1968, Ser. No. 733,133 Int. Cl. B64c 11/36, 11/04 US. Cl. 170160.59 4 Claims ABSTRACT OF THE DISCLOSURE Because of problems caused by airborne debris in some environments where internal combustion engines are used, it has been customary for manufacturers to fit certain types of engines with fans upon which the pitch of the blades can be reversed. Generally, this requires that the blades be loosely fitted in a hub part and held in place by small pins, washers or other devices. This creates a hazardous situation because upon failure of such holding device, the blade can be thrown outwardly with considerable force.

It is the object of the present invention to provide a reversible fan of extremely strong and dependable construction, wherein the blades are retained in their position of adjustment by a light spring so that they can be readily readjusted, but wherein the failure of the retaining spring does not release a blade or necessarily interrupt operation of the fan at all. Further objects and advantages of the invention and the manner in which it is carried into practice are made apparent in the following specifications wherein reference is made to the accompanying drawings.

In the drawings:

FIG. 1 is a view in front elevation of a portion of a fan embodying the present invention;

FIG. 2 is an enlarged fragmentary portion of the fan shown in FIG. 1 with a part shown in section on two angularly relating planes shown at II-II in FIG. .3, and

FIG. 3 is a view taken from the inside of the blade supporting ring as viewed from the plane IIIIII of FIG. 2.

The principal parts of the fan are illustrated in FIG. 1 as blade assemblies one of which is generally indicated at 10, a blade suporting ring 12 and retaining springs 14, each blade assembly comprises a blade 16 and, as best shown in FIG. 2, a trunnion-like shaft 18 which has an enlarged inner end 20 thereon and a further enlarged inner portion 22 from which a key 24 extends radially. The blade supporting ring 12 is made in two mating parts, which are placed together and drilled to provide bearing ice bores for the trunnions 18 and holes for bolts shown at 26 for holding the two parts of the supporting ring together before its assembly into an engine. Other holes are provided for a circle of cap screws 28, one of which is shown in FIG. 3 as extending through both parts of the supporting ring into a plate like part 30, which is a portion of a hub (not shown). The hub is rotated in any suitable manner by the power of the engine which the fan serves to cool.

The two parts of the plate supporting ring are shown at 32 and 34 in FIG. 3 and the part 32 is shown as having two key slots 36 and 38 disposed at an angle to the flat face of the supporting ring which is a desirable angle for the pitch of the fan blade. The key 24 on the inner end of the trunnion part 18 is disposed in one of the slots as shown in FIGS. 2 and 3, and holds the blade against rotation about the axis of the trunnion. One of the springs 14 is provided for each of the two blades and the spring is shown as a flat leaf type spring curled at its ends for engagement with a shoulder 42 at the outer end of the trunnion. The springs are bifurcated at their ends as shown in the sectioned part at the right of the spring shown in FIG. 2 so that they bear with equal force upon opposite sides of the trunnion and are prevented from rotating or sliding out of place at their center contact with the outer periphery of the support ring.

To change the angle of the blade shown at 16 in FIG. 3, it is simply pressed inwardly with sufficient force to overcome the force of spring 14 and then rotated until key 24 can be received in slot 36. This changes the angle of the blade to the position in broken lines shown at 16 in FIG. 3 which is the exact opposite functionally from that shown at 16.

The inner end of the trunnion 18 is shown with one beveled side best seen at 46 in FIG. .3. This is a construction adopted to facilitate forging of the trunnion and is not pertinent to the invention.

One very advantageous feature of the invention is that the blades are at all times held in position by heavy durable elements, the only relatively weak member being the spring 14. Upon failure of the spring 14 during operation of the fan, no interruption in service would be experienced because the blades are held in their position of angular adjustment by centrifugal force. When the fan comes to rest it is possible the blades which were held by the broken spring could drift inwardly and lose their orientation. This however, would be readilly recognized and easily corrected.

What is claimed is:

1. A reversible fan comprising a plurality of blades, a trunnion at the inner end of each blade, each trunnion having an enlarged inner end, a blade supporting ring having spaced radial bores to receive the trunnion with its enlarged end limiting radial outward movement of the blade, a radially projecting key at the inner end of the trunnion, and two angularly related key slots to receive the key to hold the blade in either of two positions of opposite pitch.

2. The fan of claim 1 in which the blade supporting ring is made in two parts abutting on a plane intersected by the axis of the radial bores.

3. The fan of claim 1 in which the trunnions have enlarged portions forming shoulders spaced outwardly 3 4 from the blade supporting ring, and resilient means acting 1,685,323 9/1928 Hansen 170--160.59 between the outer periphery of the ring and said shoulders 3,026,943 3/ 1962 Huber 170-160.59 to prevent inward movement of the blades and removal 3,174,553 3/1965 Spears 170-16059 of the keys from their slots.

4. The fan of claim 3 in which the resilient means 5 FOREIGN PATENTS are leaf springs bifurcated at opposite ends to embrace 11189960 3/1959 Francetwo trunnions and engaging the periphery of the support- 575,578 2/1946 Great i i ing ring centrally between the trunnions. 638856 6/1950 Great Bntam References Cited 10 EVERETTE A. POWELL, 111., Primary Examiner. UNITED STATES PATENTS U S C1, X R

1,485,552 3/1924 Colby 170-16059 170-16011 

